Anybody Use Performance Welding Headers?

[SSDiv6]

Originally Posted by Jeff Lee

Back to the original question, stainless does offer a HP improvement. The pulses react differently to stainless than steel tubing. I can't say that from experience as I've never had the pleasure to own such a set. That's what my engine builder says. He also says some internal coatings (not ceramic based) are a good alternative. He DOES have the before / after to back up the stainless or coated headers vs. regular steel.
Maybe our engineer SSDiv6 can chime in...

I will keep it simple because header design is a science that involves many parameters and the discussion can go for years due to the many theories and principles.

The use of stainless steel as header material does not have anything to do with exhaust pulses. The dampening of the exhaust pulse can be controlled with any steel if you vary its thickness or gage. In fact, the aircraft industry uses Inconel. The real factors are undisturbed exhaust gas mass and density, MACH/Supersonic exhaust speed and the heat transfer advantage the stainless steel material offers.

Because mild steel headers will deteriorate due to heat and corrosion, many racers will coat the headers internally to make them last longer. Do not get me wrong, keeping the heat inside the headers for a short time, is a good thing. However, when you coat the headers internally it has other effects such as reducing the exhaust velocity, and as a result, affecting heat transfer. Therefore, when you have a stainless steel header, you do not have the issue of reduced exhaust velocity and heat transfer because you do not have to coat the header internally.

Exhaust coatings have their place in applications of extreme heat such as turbocharged engines. In this type of application, a Ceramic coating is beneficial because too much heat can slow down the supersonic exhaust velocity downstream.

Again, it is an issue of much you want to spend. If you have a mild steel header and coated for longevity, you will give up some power. If you have the money, a well-designed stainless steel header will give you longevity and power. I said, “well designed” because I have noticed too many cars at the track with header designs that are either too big, too long or too short for their intent.